This invention relates to electrostatic devices having a fixed electrode, an insulative layer and a variable resilient electrode that is electrostatically attracted to and extends over the fixed electrode to cause a change in the transmissivity or the reflectance of electromagnetic radiation such as heat or light. The invention more particularly relates to such an electrostatic device wherein the fixed electrode is split and the electrical activating voltage is applied between two fixed electrode pieces.
A large number of electrostatic devices with a resilient variable electrode are known. In each instance an activating voltage is applied between the fixed and the variable electrode. It is usually preferred to make the variable electrode of a thin plastic sheet having a film of aluminum deposited on at least one side. In the patents U.S. Pat. No. 3,897,997 and U.S. Pat. No. 4,094,590 to C. G. Kalt, issued Aug. 5, 1975 and June 13, 1978, respectively, and assigned to the same assignee as is the present invention, there are described a number of such devices. It was first noted that mounting and electrically terminating such delicate plastic material is very difficult to do without creating wrinkles, that emanate from the region of mounting and terminating, which wrinkles interfere with the uniform bending of the variable electrode when the device is activated. The problem of making reliable contact with the thin aluminum film that carries an air induced oxide is especially difficult. The electrical contact is usually needed in the same region of the variable electrode at which it must be mounted. Whether that involves soldering, welding, staking, or providing a deposit of conductive resin or a pressure contact, it represents a potential source of distortion and wrinkling in this critical mounting region.
It is an object of the present invention to provide an electrostatic device having one or more variable electrodes that do not require ohmic contact thereto.
It is a further object of this invention to provide such a device that is simpler in manufacturing leading to greater reliability and lower cost.